// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
using System;
using System.IO;
using System.Net;
using System.Text;
using log4net;

namespace KnessetCore.Fetchers
{
	/// <summary>
	/// Fetched data from the internet. Initialize the class with a specific URL address and fetcher will fetch
	/// the appropriate object. Pay attention that the fetched data will be treated as a string therefore trying
	/// to fetch binary data will be unpredictable.
	/// </summary>
	public class HtmlFetcher : IFetcher<String>
	{
		/// <summary>
		/// Holds the address from which we fetch the desired object.
		/// </summary>
		private readonly String address;
		private readonly ILog logger = LogManager.GetLogger("KnessetCore.Fetchers");

		public HtmlFetcher(string address)
		{
			if (address == null) throw new ArgumentNullException("address");
			this.address = address;
		}

		#region IFetcher Members

		/// <summary>
		/// Fetch information and return it to the user.
		/// </summary>
		/// <returns>Fetched information. Can be null.</returns>
		/// <exception cref="FetchException">Error while trying to fetch data.</exception>
		public String Fetch()
		{
			logger.Debug("Entered HtmlFetcher.Fetch");
			// Holds text read from html page.
			string text;
			try
			{
				// Create a request for the URL. 		
				WebRequest request = WebRequest.Create(address);
				// Get the response.
				WebResponse response = request.GetResponse();
				Stream stream = response.GetResponseStream();
				// Now slurp the object.
				StreamReader reader = new StreamReader(stream,Encoding.Default);
				text = reader.ReadToEnd();
				logger.Info(string.Format("Fetched from {0}", address));
				logger.Debug(string.Format("Fetched the following data: {0}", text));
			}
			catch (Exception e)
			{
				logger.Error(e.Message);
				throw new FetchException(e.Message,e);
			}
			logger.Debug("Exited HtmlFetcher.Fetch");
			return text;
		}

		#endregion
	}
}